Sadly, you have cut off the cotyledons ie the seedlings very first leaves. It cannot survive after that.

Did you cut off those 'first leaves' or did you just clip off the tips? You don't say. As floral said, those are called cotyledons and it is OK for the tips to be a little dry looking... like in your photo. the real leaves will follow.

one leave was dry looking and the other one was black and seemed rotted of soggy so i thought it spread

OUCH! Even if it doesn't die I don't see how you could expect it to forgive you for whacking it's cotyledons off.

Sounds like some damping off going on. Desk fans very worth $15

I don't think we're looking at damping off in that picture. Damping off is stem rot where the stem meets the soil. But without any more info, it's hard to say. That being the case, fans do dry out the surface, which would prevent damping off. Another way is just to use sterile soil. Ever since I started doing the latter, I never get damping off.